Light utilization optimization of semi-transparent perovskite solar modules via constructing p-n homojunction for efficient four-terminal tandem devices

The low light utilization efficiency (LUE) in semi-transparent perovskite solar modules (ST-PSMs) poses significant challenges to their power conversion efficiency (PCE) and potential integration into four-terminal (4-T) tandem cells. In a groundbreaking development, we have introduced a novel approach by incorporating tin oxide nanoparticles (SnO₂ NPs) into the perovskite solution. This innovation has led to the construction of p-n homojunctions within the upper layer of large-area films. Our strategy has not only enhanced the built-in electric field through the p-n homojunctions, but also improved the circulation of visible light within the perovskite film via NPs scattering. This dual action has improved both charge transport efficiency and light management, thereby significantly optimizing the LUE of ST-PSMs. As a result, the 56.9 cm² ST-PSMs have achieved a certified PCE of 17.2 %. When mechanically stacked with silicon heterojunction (SHJ) solar cells to form 4-T tandem devices, an impressive PCE of 27.2 % was realized. This pioneering strategy paves the way for a new paradigm in enhancing the performance of perovskite tandem solar devices, offering a promising avenue for future solar energy applications.